Non-grounded or metallic line-circuit system.



H. H. BURFIEINDi NONAROUNDEB GR mErAmc UNE mecum sYSEM.

APPLICATEN FILES APH. 18. ISO?.

Patented Apr. l, 1919.

3 SHEETS-SHEET R. H. BURFHND.

NON-GROUNDED 0H METALLIC UNE CiRCUIT SYSTEM.

APPLlcAUoN man APR. le. wor.

1,999, 1 19. Patented Apr. 1, 1919.

3 SHEET S-SHEET 2.

AH. H. BURFEIND.

NON-GRUUNDED OR MEALLIC UNE CIRCUIT SYSTEM. APPLICATION FLED AFR. i8.39u?.

1 ,299, 1 l 9. Patented Apr. l, 1919 3 SHEETS-SHEET 3.

.UNITED sTATEs PATENT OFFICE.

` namen n. BUBFEIND, or cnIcAeo, ILLINOIS, AssIcNoa, er 1an-simAssmimrENTs, To AUTOMATIC nnncrarc company, A coaroaA'rroN or ILLINOIS.

NON-GROUNDED 0B METALLIC LINE-CIRCUIT SYSTEM specification of Lettersraient.

Application filed April 18, 1907. Serial No. 369,021.

To all whom 'it man concern:

Be it known t at I, RAYMOND rH. BUR- FEIND, a citizen of the UnitedStates of 'Amer1ca, and resident of Chicago, Cook county, Illinois, haveinvented a certain new and useful Improvement in Non-Grounded orMetallic Line-Circuit Systems, of which the following is aspecification.

My invention relates to automatic telephone systems in which means areprovided or enabling a calling subscriber to extend his line intoconnection with the line of the called` subscriber, or into connectionwith some other line, without the aid of operators.

The principal object of my invention is the rovision of an improvedsystem in whic the apparatus at the exchange or central station may becontrolled by the calling subscribers, for the purpose of' establishingconnection with the lines of the called sub scribers, or for the purposeof disconnecting and restoring the automatic switches after thesubscribers are through talking, Without employing operating grounds atthe substations-that 1s to say, Without employing ground circuitsbetween the substations and the central station.

It is also an object, of course, to provide certain details and featuresof improvement and combinations tending to increase the ,generalefficiency and serviceability of an automatic telephone exchange systemof thlJ particular character. v

In application No. 369,013, liled April 18, 190 by A. E. Keith forimprovement in non-grounded or metallic circuit sylstems',

a system is shown in which the switc es are operable without the'necessity `of using ground connections at the subscribers stations.acaole, sled April 18, 1907, by E. A. Me1 linger, a system is shown inwhich a plurality of automatic switches are successively controllable oroperable 'witlout using grounds at the substations, and these switchesare also releasable in the same manner. VMy

resent invention is, therefore, in the nature of an improvement on thesystems thus disclosed in the said prior Keith and Mellingerapplications.

j n` he accompanying drawings, Figures 1 and 2 taken together representdiagrammatically a 'calling substation A connected by 'means of centraloffice switching apparatus with'a called vsubstation A', in asystem em-Also, inl application SeIMlMNo.

bodying the principles of my invention. The switches, through which thestations A and A are shown connected, comprise, in Figure 1, theso-called first-selector() and second-selector D; and in Fi 2, aconnector E and a first-selector C similar to the vfirstselector C. Theselector C is individual to the line of the substation A, While thefirstselector C is individual to the line of the I substation A', #2220.The said selectors C and Q are substantially the same in construction.For operating the central oiice switches there is provided a centralsource of current or battery B having its positive terminal preferablygrounded at G (Fig. 2). Figs. 3, 4 and 5 are detail views of thesubstation impulse springs` Figs. 7 and 8 are detail views of thePatented Apr. 1,`1919 release relays oi.l the selector and connectorswitches.

It will be understood, of course, that in this system thefirst-selectors are arranged in groups, as well as the second-selectorsand the connectors. A somewhat common arrangement is to divide thesubstations into groups of one hundred, and to, of course, divide theirallotted Selectors into correspondlng roups. Furthermore, every group offirst-sc ectors has {allotted to it. a group of second-selectors .forevery bank level. Through' the medium ofthe second-selectors theconnectors of various hundred-.groups are reached. The connectors andsecond-se.- lectors are less in number an` the .sub- Scribers-that is,they are employed on a percentage basis. The substation A may be of anysuitable or approved type. The one in connection with which` I haveelected to illustrate my invention comprises a receiver 2, switchl1opk 3for controlling the sub station circuits, which controlling operationsare accomplished through the medium of any suitable means, such as tbecam-arms 4 and 5. When the switch-hook'is down,

:the cam-arm 4 carries the spring@ out of engagement with ,the sprin 7and into engagement with tli'e spring thereby bridging the ringer 9 inseries with the condensers 10 and 10*l across the line. Furthermore,when the switch-hook is downtlxe said cam disenga es the springs 11 and12, thus breaking thel ocal circuit which includes in `series theprimary winding 13, transmitter 14 and local battery 15. l.The saidsubstation -com- .prises ,this usaal induction-coil 16 11a-Vilas *11primary winding 13 and secondary winding Being an automatic substationit is provided with the usual vertical and rotary impulse springs 18 and19. Said substation is, of course, provided withma dial, which is notshown but which is secured lto the shaft 20, together with. the lockingdog 21. Furthermore, there is a locking cam 22 that locks the do 2l,while the receiver is on the switchook, to prevent a rotation of thedial. For operating the impulse springs 18 and 19 (Fig. 3) thesubstation is provided with an impulse Wheel 23 that is secured to theshaft 20, which impulse wheel carries on its eriphery the so-calledvertical impulse teetli 24 and one rotary impulse tooth 25. The saidimpulse teeth are so arranged that When'the dial is drawn down theimpulse S rings 18 and 19 are not operated 3 ut as t e dig] returnsfYfirst 1the vertical8 (th ex)i et e vertice im u sesprin 1 ig. 4 after"theyY havia) complete their work the rotary impulse tooth 25 operatesthe rotary impulse sprin 19 (Fig. 5). In this operation the vertica imulse spring 18 is `pressed into contact witi the spring 26,

whereby the vertical line conductor 27 becomes connected directly withthe rotary line conductor 28. Normally, when the receiver is removed,the vertical and rotary,Y line con- 'I ductors 27 and 28 are connectedthrough the 'to a scriber may signal the called subscriber com.-

"Pressed, carries fthespring 32 into eng e?.

highresistance coil 29. After the verticaly impulse teeth have operatedthe vertical impulse spring 18, thyrotarl impulse momentarily disengagestie springs 19' and 30, whereby the line conductors 27. and 28 become sarated/g andwvhen thesprings engage, the ine ,conductors 27 and y28 areagain connected ttrdggh uitleen/29. n wifi be clear fromthe/drawings'that when the subscriber rotates the v"dialthe rota yimpulse tooth 25, uponreturning or r tlng in a counter-cioe iscdirection, meets the angled member sh 'Yamini/the end of thenspng 19preizg Alit/aaliiees, both s r1 19A and '30 out of necti However, whenthdial returns towar 4normal position the rotary impulse tooth 25 comesin behind the member on the 'end of the sprin 19 away from t e spring30, thus breaking the circuit as described. It will be understood,furthermore, that 'the shaft 20- is provided with a sprin adapted torestore the dial Vwhen once it lies been rotated out of normal osition.Furthermore, the switchhook 3 is also provided with any suitable sprinwhereby said switch-hook may be cans Y to rise when the weight of thereceiver 2 is removed. e means' whereby the subuSh-button 31 which, whenment wi'thfthewntact point 33, whereby te B codutm'sgl 28 are connected.

wlper and release relay wi tlie/w/ay,y but without fea `ngvconintoengagement with the V19, llexing the-said spring Spring 32* .magnet 64energizes, the armature through the private wiper 37 The first-selectorswitch/sho nntCmaybe of any suitable or appr ned ty ,for instanfe of thegeneral type described in United States Patent No. 15 321, granted`March 13, 1906, to Keith, rickson and Erickson. Among other details, itembodies the following well-known devices and circuits: The switch shaft34 carriesthe vertical and rotary wipers 35 and 36, respectivel and theprivate wiper 37. The side swltch is well known and comprises the sideswitch wipers 38, 3.9, 40, 41 and 42, which may be designated as thevertical rotary and priaate side switch' wipers, the rotary 4magnet er,respectively. The side switch is under t e control of the private magnet43, and when the side switch 1s in normal or lirst position the wipers38, 3.9, 40, V41 and 42 occupy the contact oints 44, 45 46, 47 and 48,respectively. n the second position they rest on the contact points49,50, 51, 52 and 53, respectively, and in third osition the contactpoints 54, 55, 56,` 57 and 58 are engaged by their respective wipers.Through the medium of the vertical line Yrelay 59, and while the sideswitch is in first position, the subscriber cont ls the vertical magnet60, which latter operates to raise the switch shaft 34 and wipers 35,36and 37 vertically. By means of the rotated to disengage the springs 62and 63, the' subscriber controls the private magnet 43 and,'therefore,the side switch. While the side switch is in second position the rotarymagnet 57, which operates to carry the switch shaft and wipers 35, 36and 37` in a rotarydirection, is energized.- The relay 63 provides themeans whereby the subscriber controls the release magnet 64 while theside switch is in the first or second position, and while the switchshaft is -oi normal. Tf, while the sideswitch of the selector (l is in lfirst or second position, the relay 63 is energized; and the spring 142,upon the end of which there is a latch 31l lFig. 6l, is carried out ofengagement with t e spring 143 and spring 32, the latch 31* then fallsover the; end of the 142 in contact (Fig. 7). Now, when the ref`lay`63denergizes, the two lockedsprings` 32" and 142 are carried intoenlgagement;

with the spring 143; then when t tracted and' moves the latch 31* insuch mannerV that it turns about its pivot oints on" the end of thesprin 142 and un ocksthe (siprings 142 and 32, w ereby the Ytwo sprin sisengage. If the side switch passes to t e third position, then, sincethe selector Cis of the trunk-release type, the selector is con-i.trolled throti Y i nection with the latter lis, then established ,rotaryline relay 61,l and before the shaft has and locks thetwo. springs 32*and 115 e relata* i 33* is 'attr 'e130 h the next switch, and a conitsby mms 4un` of the back-release relsy The bridgeout-olf relay 66 isprovided to open the connection between the line relays 59 and 61 andthe battery terminals. It will be noticed that the vertical line relay59 is connected to the nen-grounded terminal, and that the rotary linerelay 6l is connected to ground, This disconnection is desirable,because if the reiays are not disconnected from battery, the ringingcurrent for signaling the subscriber may then operato either or both ofthe relays 59 and 61 and canse some interference with the switch. It isalso desirable to remo ve the bridge formed through the said relays'from across the line so es to give the voice-curren ts es clear a. pathas possible. Furthermore, the shaft 34 is provided with the com 66which, when the shaft is in normal position, permits the springs 62 and63 to disengege; but on the first verti Cal step of the shaft 3l. thecom 56a presses the said springs into engagement. Now when the shaft isgiven a rotary step the com 60 is carriml out of engagement with thespring 03, and the springs 62 and 63a disengnge. The switch-sl'iaft isprovided with n normal arm 67 which, when the shsft is given c verticalimpulse, permit-s the springr 70, which nornmlly engages the spring 68,to poss into contact with the 4 spring 71.

The Second-selector D is similar to the first-selector C, with theexception that thereare no normal conductors, such as the normalconductors 72 and 73. Since there is no use 'for such conductors theyare omitted. There is also no utility in the second-selector for ebridge-cutoff relay, such as the relay 06 .of the selector C, and thisis also omitted, and the line releys are connected `directly to thebattery *termi` nais. The private normal conductor, such as the privatenormal conductor '54; of the selector C, is of no use in connectioliwith the second-selector and is also omitted. Since like parte aresimilarly, represented throughout the drawings, the 'verticsl magnet 75and the rotary magnet 76. the release magnet 77 end the private magnet78 `will be recognized and` understood. The scid privato magnet 73, ofcourse, controls the sido switch wipers T9, $2.0, iii, and 83. Thevel-tieni movomcnt of the switch shaft #il and. therefore, of the wipers85, 8G and 97, is wntrollcd by the vertical mag nel.y '75, and therotary movement by the rotary magnet 70, the rotsry magnet circnii beingprovided with the usuel interruptor springs 88. Thooperative magnets ofthe switch are. of course. controlled by the subscriber through themedium of the vertical und rotary line relays 89 and 90, as is wellknown. Said relays have under their control the usual springs 91, 92 and93.

The selector D `is also provided with a release relay 94 for controllingthe release of the switch when the side switch passes to third position.The relay 95 controls the energizing circuit of the release magnet 77While the side switch is in Erst and second `positions and the shaft isolf normal. The

release controllin relay 95 in the second-` seector operatesin the sememanner as the release relay 63 of the irstselector.` If,

while the scid switch of the selector D is inrst or second position, therelay is energized, and the spring 99, upon the end of which there is alatch 100, is carried out of engagement with the Spring 101 and intoengagement with the spring 10Q., the so latch then falls over the end.ofthe spring 102 and locks the two springs 102 Vsind 99 in contact witheach other. Now when the relay denergizes, the two locked springs arecarried into contact with the 35 spring 101. Then when the releasemegfnet 77 energizcs, the armature 108 is atof the Igeneral typedescribed in United States stent No. 815,176, granted March 13, 1906, toKeith, Erickson and Erickson. 100

The mechanical details of the first-selector and connector, as is Wellknown, are ver much the same. The connector switch sha t 104, like lthefirst-selector switch shaft,` carries the line Wipers 105 and 106 andthe 105 private wiper 107. The connector switch 1s also controlled bythe calling subscriber through the medium of the vertical and rotaryline relays 108 and 109. The vertical line relay directly controls thevertical 110 magnet 110, and. also the rotary magnet 111 and the ringerrelay 112. The olice of the vertical magnet 110 is to give the shaft andghat wipers their vertical motion, and the rotary magnet to the shaftand shaft wipers a. rotary or circuler motion. The rotary line relay 109controls the energizing circuit of the re-V lesse relay 113. The releaserelay 113 is similar to tor, and when the relay 113 is energized thespring 129 is shifted out of engagement with the Spring 180 and intoengagerhent with the spring` 131 (Fig. 8). The latch 1.9 then locks thetwo springs in contact,

111 imparts 115i the relay 95 of the second-selec- 120 contact with thebev- 130 it returns to normal eled member 134,' vvhereby the latch 132,gradually slides from the end of the spring 131; and when the saidspring is unlocked osition, out of engagement with the spring 129. Theprivate magnet l114 is controlled by the vertical Aline relay 108, and.under certain conditions controls the release magnet 120 and also theside switch yWipers 115, 116, 117, 118 and 119. The side switch of theconnector, like the side switch of the first-selector, has a normal orfirst position, a secondposition and a third position. The releasemagnet 120 is also controlled by the relay 1.21. By the condenseis 122and 123` the circuit through the connector is divided into two sections.The central ofiice is equipped with busy-signaling apparatus of anysuitf able design, as, for example, the one comprising an`interrupter122 in series with the primary Winding 123* of the inductionlcoil 124,whereby a busy-signaling current is induced in the secondary winding 125of the said coil. The connector switch shaft 104 also carries a normalpost arm 126 which, when the connector shaft is ofi' normal, allows thespring contact point 128, whereby the busy-Signal may be transmitted tothe rotary line conductoi.

The substation A is like the substation A; also, the lirst-selectorswitch C allotted to the line #2220 is like the first-selector Callotted to the line #5000.

A clearer understanding of my improved system may be had from an eXlanation of the operation of the central o ce switches when onesubscriber calls another. Suppose, for an example, that the subscriberat substation A desires to communicate with the subscriber at substationA on the line #2220. The operation of the central oilice switches, tobring about this connection, is as follows: When the Subscriber atsubstation A removes thefreceiver 2 from the switch-hook 3 the cam-arm 4permits the springs 7 and 6 to engage. whereby a series circuitincluding. the vertical line relay 59 i of the selector C,resistance-coil 29 of the substation A, and the rotary line relay 61 ofthe selector C, is closed. This circuit extends from ground G at theselector C through the springs 135 and 136, through the rotary line'relay 61, contact point 45, side switch Wiper 89, rotary' lineconductor 28, through the springs 30 and 19, springs 6 and 7, secondaryWinding 17, receiver 2, through the resistance-coil 29 to the verticalline conductor 27, side switch Wiper 38, contact point 44, vertical linerelay 59, springs 137 and 138 to the battery lead 139, thence throughbattery B and to ground G. The rotary line relay 61 is so adjusted thatthe current-How is sufficient to operatiyely energize the said relay,While the vertical line 'eratively energize which latter, springs K144127 to engage the through the private ma separates the springs 142 and143, and places the spring 142 When the dial is rotated for the rstdigit 2 the spring 18 is twice pressed into contact with the spring 26.By this operation the line conductors 27 and 28 are directl connected,shunting or short-circuitin t'e resistanoe-coil 29; thus a newcircu1t,.which does not include the resistance-coil 29, is es tablishedthrough the vertical' and rota.

line relays 59 and 61 of the selector C. Su icient current now flows inthe circuit to opupon energizing, presses the and 141 into contact,which closes an energizing circuit through the Vertical magnet 60.ground G2 through the .springs 141 and 144, through the vertical magnet60 to the battery lead 139, thence through battery B and to ground G.The springs 18 and 26 being twice pressed into Contact for the firstdigit, the vertical line relay 59 is twice operatively energized, andthe vertical magnet is in turn energized twice. By this operation of thevertical magnet the shaft 34 and the shaft wipers 35, 36 and 37 areraised two steps in contact with the spi-in 32. H

the vertical line relay 59,

This `circuit extends from and brought opposite the second bank level.

It should be borne in mind that at the first vertical step of the switchshaft the cam 66'L operates to close in contact the normally o en shaftsprings 62 and 63. .As soon as tie said springs 62 and 63 come intooontact an energizing circuit is established G2 at'the selector C trough the springs 141 and 140, through the cam springs 62 and 63 to theprivate magnet 43, thence'thro'gh said magnet to the battery lead 139,and

et 43 from ground.

through battery B to ground G. Furthermore, at the same first verticalstep the normal post arm 67 disengages from the spring 70, permittingthe latter to leave the spring 68 and to engage with the grounded spring71. This operation, of course, disconnects the private normal conductor74 from the bridge-cut-oil relay 66 and places a guarding potential onsaid private nox-mal conductor from ground G1 to prevent any callingsubscriber from calling in upon the line #5000 after the switch C hasbeen operated.

The rotary impulse tooth 25 separates the springs 19 and 30, which openthe circuit including the vertical and rotary line relays andreaistance-coil 29. The rotary line re lay (Slt being deprived of itsenergizing cur rent, denergizcs and permits the springs 141 and li) toseparate. whereby the energizing circuit ot the private .magnet 13 isbroken, and the side switch permitted to pass to second position. Assoon as the im- 'pulse tooth 25 disengages from the spring 19, thesprings 19 and 30 again come into contact, and again the energizing'circuit through the rotary line relay is established. In the meantime,however, the circuit through the release controlling rela;Y 63 isbroken, hut the relay being a slow-acting relay suliicicnt residualmagnetism is retained in the core t0 maintain the relay in an operatedposition until this energizing circuit is again established, when therotary line relay energizes. When the side switch passes to secondposition an energizing circuit is established through the rotary :nagnet57". This circuit extends from the grounded contact point 52 through theside switch wiper 41, interrupter springs 145', rotary magnet 5T to thebattery lead 139, thence through battery B and to ground G. 'The rotarymagnet, upon energizing, operates to carry the shaft Wipers in a rotaryor circular direction. The rotary magnet being energized, the shaftwipers 3G and 3i' are carried one step and. into engagement with thebank contacts that constitute the terminal of the trunk line leading tothe selector switch D, assumingr that the trunk leading to the saidselector leads off from the first set of contacts of thu` second level;but if the first trunk line is busy soule other selector (similar to theselector C) in the exchange will be resting in engagement with saidtrunk line. and the first private bank contact `ofthe second level willbe found connected to ground, as is usually the custom in systems ofthis general character. Therefore, when the selector shaft is rotatedone step an energizing circuit is established through the private magnet42, when the Aprivate Wiper 3T strikes the tact. thereby retainingl theside switch in .second position and maintaining the ener* grizingcircuit through the rotary magnet 57a. The rotary magnet, byintermittent magnetization, thus causes the Shaft to 'rotate step bystep and carry the private wipers past the last busy trunk line.However, as soon as the private magnet is deenergized the side switch istripped into third position.; buty if there are no busy con tacts to be'passed over, as assumed in the first instance, the private magnet #i3trips the side switch to third position. Witlrthe result that the sideswitch Wipers engage their respective contact points. Wien the sideyswitch wipers 38 and 39 pass to third liosition the subscribers lineconductors 27 und are extended to the conductors leadgrnnnded privatebank con- -Y ing to the selector switch D; also, since the side switchwiper 40 engages a grounded contact point 56, a guarding potential is established at the private Wiper 37 forprotecting the seized trunk linefrom being molested by any other switch. It will be notieed that afterthe side switch passes to third position the relay 63 denergizes, andthe springs 32 and 142 engage with the spring,r 143, but the engagementof the said springs at this particular time is without effect, since theside switch wiper 42 `has passed to third position and engaged the idlecontact point 58. Furthermore, when the shaft 34 is given the firstrotary ste the cam 66=L passes out of engagement wit the spring- 63 andpermits the S rings 62 and 63a to disengage. This sisenga ment breaksthe energizing circuit formedy the rotary line rela through the rivatcmagnet 43V and leaves t e control of t e latter to the guardingpotential (when the side switch i Wiper 40 is in second position) on thepriprivate wiper 37. The second digit is called after the subscriber hasestablished connection with the seieftor D by way of the trunkconductors 346 and 147, When the trunk conductors 146 and 147 are seizedan energizing circuit is estahlshedtxhrough the vertical and rotary linerelays 89 and 90 of the selector D, in the same manner in which thecircuit was established through the vertical and rotary line relays fthe selector C. The rotary line relay 90 energizes and closes anenergizing circuit through the release relay 95. The circuit through therelease relay extends from ,ground (ir8 lthrough the springs 91 and 93.through the relay 95 to the battery lead 139, thence through battery Band to ground G. The relay 95 energizes and locks the springs 99 and 102in contact, :is explained. The subscriber rotates the dial, asdescrib'fl` for the second digit 2, thereby shunting orshort-circuitingr the re- Sistance-coil 29whcn the springs 18 and 26engagendfhe rertieal linerelay 89 now operatively energizes und placesthe springs 91 and :92 in contact, whereby a circuit is closed throughthe vertical magnet 75. said circuit extending from ground Gra-throughthe springs 91 and 92, through the magnet 75 to the battery lead 139,thence through battery B and togronnd G. Each time that the verticalmagnet is energized it operates to raise the shaft and shaft wipers onestep at a time until the said Wipers are carried two steps and broughtopposite the level in which are located the terminali; of the trunkconductors 151 and 152 leading to the connector switch E. ln the mannerdescribed in connection with the selector C when the switch shaft 94 ofthe selector l) moves up the first step. the cam 98 presses the camsprings 96 and 97 into contact,- whereby an energizing circuit is set upthrough the private magnet 78. This energizin circuit extends fromground G3 through t e line relay springs 91 and 93, through the camsprings 5 96 and 97 to the Jrivate magnet 78, thence to the batteryleadI 139, and through battery B to ground G. W'hen the rotary impulsetooth separates the springs 19 and 30 the energizing circuit through therotary line relay 90 1s interrupted, and the said relay restores thesprings 91 and 93 to normal position, which breaks the energizinjcircuit through the :irate net 78 an the release relay 9 The privatemagnet, upon denergzlng, permits the side switch to pass from first tosecond position. The release relay 95 being slow-acting, however, therotary impulse tooth disengages from the spring 19, and the energizingcircuit of the 2,0 rotary line relay is again established, and thesprings 93 and 91 again engage, closing the circuit through the releaserelay 95 before the armature of said relay has time to fall back. Whenthe side switch Wiper 81 25 engages the grounded Contact point 148 anenergizing circuit is'established through the rotary ma et 76. Thiscircuit extends from the groun ed contact point 148 through the sideswitch Wiper 81, interruptor springs 88, rotary magnet 76 to the batterylead 139, thence through battery B to ground G. The rotary magnet, byintermittent energitation, operates to rotate the shaft and shaft wipersstep by step and carry the Wipers past the last busy trunk line, if anysuch are found, as described in connection with selector C. When theWiper 87 discn gages from the last bus trunk line the energizing circuitexten ing from the rounded private contact to the private wiper 8T,conductor 149, through the release relay 94, side switch wiper 82,Contact point 150, throu h the private magnet 78 to the battery lea13,9, and through `battery B to ground G, is then broken, and the sideswitch passes to third position, thus extending the subscribers lineconductors 27 and 28 to the conductors 151 and 152 which lead to thcconnector switch` E. Also, since the side switch wiper 82 en gages thegrounded contact lpoint 153, a

guarding potential is established at the private wiper 87 for protectingthe seized trunkv line from being molested by any other switch. Ofcourse, whenl the side switch `passes to third position and theenergizing circuit is broken through the line relays 89 and 90, theenergizing circuit is, as a result, also broken through the releaserelay 95, which relay then permits the springs 109, 99 and 101 to B0come mto contact. The coming into contact of these springs when the sideswitch is in third position 1s of no consequence, since the side switchwiper 83 maintains the release circuit o en at the time. Since thesubscribers ine conductors 27 and 28 are new 'he noticed that in eachinstance when the 70 subscribers vertical and rotary line conduclors 27and 2S are extended to thc 'next switch a new energizing circuit isesteblishcd through the line relays of the new switch and through thesubstation resistancecoil 29. At the saine time, of course, the oldenergizing circuit through the line relays of the preceding switch isbroken. The subscribers conductors 27 and 28 having been extended to theconnector E the rotary line- S9 relay 109 operates and places thesprings 154. and 155 in contact, which closes a circuit through thereleasing relay 113, This circuit extends from ground G* throu h thesprings 154 and 155, through the Winding 85` of the relay 113 to thebattery lead 139, thence through battery B und to ground G. The relay113 now operates to loch the springs 131 and 129 in Contact, by means olthe latch 13:3, as explained. The subscriber 9u operates the dial forthe third digit 2, thereby energizing the vertical line relay 108 twiceand denergizing the rotary line relay 109 once. The currentVV forenergizing the vertical line relay flows from ground (it through therotary line relay 109 to the trunk conductor 152, shaft wiper 8G, sideSwitch Wiper 80, conductor 147, shaft. wiper 36, rotary conductor 28,sprin u 26 and 18 to the vertlcal line conductor 2 side switch 100 wiper38, Shaft wiper 35, conductor 146, side switch Wiper 79, shaft wiper 85,conductor 151 to the vertical line relay 108, thence to the battery lead139, and tlirough battery B to ground G. Each time 'that the vertical105 line relay is energized the line relay s rings 156 and"154 arepressed into contact, t ereby closinglan energizing circuit through theverticalmiagnet 110; also, the sprin 157 is pressed into contact withthe groun spring 110 154, whereby the energizing circuit is establishedthrough the private magnet 114. The circuit through the vertical magnetextends from ground G* thi ough the springs 15-1 and 156, 31de switchWiper 117, through the vcr-4 15 tical magnet 110 to the battery lead.139, thence throughbattery B and to ground G. Eachtime that thevertical magnet is energized it operates to raise the shaft and shaftwipersonc step at a time until the said wipers are carried up two stepsand brought opposite the level in which are located the terminalcontacts of the line #2290. The

circuit through the rivate magnet 114 eze tends from ground x* through-the springs 154 and 157 to the side switch wiper 112s, through theprivate magnet 114 to the battery lead 139, thence through battery Band. to ground G. The private magnet, -upon energizing, closes thesprings 158 and 159 in 130 i rotary impulse, l

Contact, thereby closing a circuit which locks the private magnet in enoperated position. This locking circuit extends from ground G throughthe springs 154 and 155, s rings 158 and 159, through the winding oftile private magnet 114 to the battery lead 139, and through battery Bto ground G. W'hen the rotary line relay 109 denergizes, due to the thelookin circuit through the private magnet 114 is roken. The privetemagnet now denergizes and permits the side switch to pass to secondposition, thus pla-cin the side switch Wipers 115, 116, V117, 118 an 119in connection with their respective contact points in second position.During the time in which the rotary rela 109 is`denergized 'thereleasing relay 113 1s maintained in its operated position b theresidual magnetism. The last digit ein naught the subscriber energizesthe vertice line relay 108 ten times and denergizes *he rotary linerelay 109 once. However, when the line relay s rings 156 and 154 engage,a circuit is there y closed throu h the rotary magnet 111 instead ofthrougl` the vertical magnet 110. The energizing circuit extends fromground G* through the springs 154 and 156, side switch wiper 11.7 to therotary met; net 111, thence to the battery lead 139, and through butteryB to ground G. Each time that the rotary magnet is energized it rotatesthe shaft and shaft wipers 105, 100 and 107 one step at a time until thesaid wipers are carried into engagement with the normal conductors 160`161 and 162, the first two of which lead to the line terminals of thedesired subscriber. Also, when tho vertical line relay 108 energizes,the spring 157 is pressed into contact with the spring 154, thus againclosing an energizing circuit through the private magnet 114 which againoperates und locks itself in an operated position. Thi` deiinergizutiouof the rotary line relay 109, when the rotary impulse tooth 25 separatesthe .springs 19 and 30, causes the locking circuit of the privato magnet114 to be again interrupted The private magnet doiinergizes, und our ofTwo results occurs, namely the release of the sido switch. from secondto third position, or the So-callcd busy-release of th(` Connector,which will he disclosed hereinafter. Suppose 4the former result to occurand the side .switch to pass to third position, thus placing the sideswitch wipers, 115, 116, 117, 118 and 119 in Contact with theirrespective contact pointe in third position. Then, when the side switchpasses to third position a guardingr potential is es tahlished forprotecting the called line. This potential extends from ground G theside switch wiper 119 to the shaft wiper 107 which engages the privatecontact of the called lino. The said guarding potential also closes anenergizing circuit through the cut-ofi' relay 103 of the Erst-selectorC',

through thereby rerncfi n g the bridge formedhy the rotary and eert icalline relays 114 and 115 of the selector C. The energizing circuit forthe relay 163 may be traced from groimd G tothe private Wi per 107,thence through the private Vnormal conductor 162, .switch shaft springsnector vertical iine relay 108. It Willjbe .remembered that theconnector -side switch course, when` This now causen the spring 32 isplaced -in contact? has passed from second to third position, g

and that the side switch wiper 117 'is in engagement with contact noint164, theretrol of the ringer relay 112, in the same manby placing thererticalline relay 108 in con ner in which the rotary magnet 111 comeuni der the control of the vertical line relay 108 when Athe side switchpassed .from lirst to Second position. T hereforc, when the verticalline relay 108 presses the springs 154` and 156 into contact the ringerrelay 112 is energized by a flow of coment from ground G* through thesprings 154 and 156i, side switch Wiper 117, contact point 164, ringerrelay 112 to the battery lead 139, :md from battery B to ground (l. Theringer relay,

upon energizing, shifts the springs 165 and 166 out of contact with thesprings 10i and 168 and into engagement with the springs 169 and 170.This results in separating the enlling subscriber-e line fromthecailedsubscribers line, and in bridging arrose the li ne et' the jltter theterminale ot' the ringer generator from the ringer generator H to theringer ,generator springs 100 and 165, side switch 115, ehet Wiper 105,normal conductor 160, rertiral conductor 171, :':ondenser 172, ringer173. springs 174 end 175, rotary impulse The signaling current le.therefore, sent springs 176 and 17T to the rotary line condoctor 178,'normal condl'lotor 161 shaft wiper ldideswitch Wiper 116, ringer re-`lay spring-S166 and 170, back to the ,genera-4 tor H. As soon as thecalling subscriber ceases to press the signaling button 31 the ringerrelay 112 becomes denerglzed, and

4tl'iesprings 165 and 166 resume their normall position in Contact withthe springs 167 and 168. The subscriber A', in response to the signal,removes the receiver 179 from the cwitclrhook 180. therehv removing` theringer 173 from across his line und bridging,

instead, the secondary circuit which includes the receiver 179, thesecondary winding 181 of the induction-coil 182, secondary springs 183and 175 and rotary impulse springs 176 and 177. The local transmittercircuit is closed as soon as the springs 185 and 186 en- `occurs whenthe calling subscriber restores the receiver 2 to the switch-hook 3,thereby breaking the connection between the springs 6 and? at thesubstation, whereby the energ'izng circuit through the rotary line relay109 of the connector E is broken-thatis, 'the line conductors 27 and 28are disconnected. The rotary line relay 109 of the connector E, upondenergization, permits the springs 154 and 155 to disen age therebybreaking the circuit through t e releasing relay 113. The releasingrelay 113 in turn denergizes and places the locked springs 131 and 129in contact with the spring 130, `thereby closing an energizing circuitthrough the release relay 121. This circuit extends from ground Gr7through the relay 121, springs 131, 129 and 130 to the battery lead 139,and through battery B to ground G. As the relay amature 133 returns tonormal position the latch 132 slides upon the beveled member 134 andunlocks the springs 131 and 129, as previously explained. The relay 121,upon energizing, closes the springs 187 and 188 in contact, whereby aSeries circuit is closed through the release relay 94 of the selector Dand release inagnet 120 of the connector E. This circuit vj extends fromground GB at the selector D to the contact point 153, side switch wiper82, release relay 94, conductor 149, private shaft wiper 87, conductor189, throu the springs 187 and 188, release magnet 120 to the batteryIlead 139, and through battery B to vund G. The release magnet 120,being 'ns supplied with current, energizes and operates in theWell-knownmanner to restore Vthe connector shaft and shaft wrpers totheir [releaserelay 65, private wiper 37, release y relayprings 191 and 190, throughthe windf mg 0 I y, -,ad'139, fand .throughv battery B to ground thesecond selector D. vAlso, when the release .magnet 'I7 to the batteryThe release magnet 77,111 turn `operates l armature. is attracted; the Yend 103 the latchy 100 out of engagement with 102, thus allowing lockedsprings 102 and .101 to disengage and return to normal position. Therelease rela of the selector C also energizes and p aces the springs 192and 193 in contact, whereby an energizing circuit is closed through therelease magnet 64 at the selector C. This circuit extends from groundthrough the springs 193 and 192 to the relay 64, to the battery lead139, and through battery B to eround G. The release magnet 64 operatesto press the latch 31a Out of engagement with the spring 32. and torestore the firstselector shaft 34. to normal position.

The busy-release of the connector E follows as a result of thedenergization of the rotary line relay 109, if the called line is busy.If, when the private magnet 114 deenergizes for the lust digit, thecalled line is busy a ground impulse is transmitted from the shaft wiper107 to the side switch wiper 119, contact point 194 through the springs195 and 196 to the release magnet 120, thence to the battery lead 139,and

through battery B to ground G. The re lease magnet, upon energizing,releases the connector switch shaft and restores the connector sideswitch to its first position, returning the vertical magnet to thecontrol of the vertical line relay 108; therefore, if the callingsubscriber (Figk'l) now presses the signaling button 31 and energizesthe .vertical line relay 108, the latter now operates the verticalmagnet 110. The vertical magnet in turn so raises the switch shaft thatthe normal post 126 permits the switch shaft spring 127 to engage thecontact point 128, and a busy-signaling current is sent to the callingsubscribers station. The calling subscriber, upon hearing thebusy-signal, will understand that the desired line is in service, andwill release the switching apparatus over the same circuits previouslydescribed The functions ofthe relay `03 of the selector G and the relay95 of the selector D are to release before the side switch has passed tothird position. Suppose that in making a call the selector C has beenoperated and established connection with the selector D, and that it isdesired to release the seieetor C and make anew call. In that event,when the subscriber restores the receiver2 to the switch-hook 3 andseparates the line conductors 27 and 28, the energizing circuit throu hthe rotary relay is then broken, and t e springs 91 and 93 separate,whereby the circuit through the release relay 95 also becomes broken.The springs 102 and 99, which are locked in contact, now engage thespring 101, whereby an energizing circuit is completed through therelease magnet 77 of ge selector D in series with the release relayofthe selector C. This circuit extends from ground Gra through therelease relay 65, shaft wiper 37, through the springs 102, 99 and 101,side switch 83, contact point `or second position by the breaking of theenergizing circuit through the rotary line relay 61,- thus permittingthe springs 140 and 141 to disengage, whereby the circuit through thcprivate magnet 43 and release relay 63 is also bmkeu. 'lhe lockedsprings 142 and 32 engage the spring 143, thus closing a circuit throughthe release magnet 64.4 This 4circuit extends-from ground GI through thesprings 32, 142 and 143, side` switch` wiper 42, contact point 53 to therelease magnet 64, thence to the battery lead 139, and-through battery Bto ground G.

The relay G3 may be wound t0 any suitable resistance', but good resultshave been obtained when said rela is wound to a resistance oftwenty-dimmJ hundred ohms; the release relay 95 may be` wound to aresistance of.twenty-three hundred ohms; the vertical linerelays-59, 89and 108 to five hundred ohms; the-rotary line relays 6 1, 90'and 109tove hundred ohms; and the substation resistanre-coil 29 to threethousand ohms.

vFrom the foregoing it will be seen that by my invention I provideimproved meansvfor controlling a plurality or series ofl auto- 'rnatiestepby-step switches without empio I l mg operating grounds at thesulistations. lufs other' words, I employ a series of switches fortrunking u calling subscriber into connection with n called subscribersline, and.4

do -so by improved means comprising line circuits including both sidesof the line in series, no grounds beim;r necessary outside of thecentral station or exchange for controllingrthe trunking switches andconnectors. In this way the subscribers telephone lines are free fromoperatingr grounds outside of.v

the exchange or centrall station and all line circuitsl employed forcontrolling the exchange apparatus are of an entirely metalliccharacterand vdo not' include1 the 4ground. The advantagesaccruing from the useof nongroundcd telephone lines and substations are many, and will beobvious in the art. What `I claim asluy invention is:-

1. hitelephone exchange system comprising -aftleihone line, an automaticswitch rov'ided with a switch shaft supportedfor both en dwise androtary motiominealis foi' closing the two sides of the line together je'movethc shaft-cndwsc, means including a A linerelay responsive to suchclosing of the line-` f or giving the shaft a susphystep end\vise,`ni`otion, suitable means for rotating thel shafti'fter it hasbeen moved endwlse, means f-f ,eee-v cuit between saidillnes,4 current,a relay ada,

to those skilled naming for cutting; olf e line relay while the shaft isin its rotaie position, and means forrestoring the shaft to normalposition by the opening of the line.

2. A telephone exchange system comprising a telephone line, an automaticswitch provided with a bank of contacts arranged 1n a plurality oflevels, a rotary switch shaft adapted to be raised to any one of saidlevels, a subscribers device for closing together the two sides of theline, meansinpluding a line relay responsive to the closin of the linefor raising the switch shaft, a apted to step the latter up to anylevel, according to the number of times the line is closed, means forautomatically rotating the shaft at any level toV find an idle contacttherein, means for outing 'oil' the lin'e relay while the shaft i ving asubscribers telephone line, an automatic switch provided with a rotaryand endwise-movable switch shaft, a line relay'4 for controllingtheendwise" movements of said shaft, means including another linev relay.for controlling the rotation of the shaft,

line circuits for energizing said relays, and means 4 forcuttng oil'Vgsafd relays -wlnle the shaft is in its rotated .positiomeaeh lmecircuit including the .two sdesof, the telephone line-nseries. j k

,bei A` telephonqgexehange 'system comprisnga subscribenstele hone lineincluding a jcri uctois, an yautomatic switch, a cubeta le, calling?device ada ted by t its backwartl'iiotauon tintermittent y closetogether thetwo talkin conducors of the telephone line, ,a line re ay insaid switch for responding to the intermittent closing f the linelneansforthereafter cutting off said relay',indlians for restoring theswitch to normal position by opening the-line.

5. A tfe'flmue exchan e system comprising'a ralhng telephone ine, acalled telephon(` liuc. a pregressively; movable selector and connectorfor establishngjajtalklng cirafsouceizof ringing 'Svlenenergized tobridge the sour-ceo l"irlgtrlgcurrent across the called cuit for.saidjrelay^,.f1fsecond "relay for controlling said energizingcircuit, aline circuit Afor said, second. relay; `a.subscribers device for siiiline circuit, 'said line circuit 'i the ytam' i c "cuit 'for-'-said`maet fpa from the tlf, from the sleoritjtliey ,nnettonand'a third orblink-#release controllingy said resubscribenfslinean energizing cusideshet 'the calling line in i series', a 'f tjlaermagnetfor saidconnector, a

system compris- :Lo i

phone lino, trunk lines includingr a pair of talking conductors and aseparate release conductor, automatic switches for uniting said trunklines to establish a connection botwm-.n said telephone lines. means forSignaling the called subscriber hy closing to gather the two sides ofthe calling line after t'he said telephone lines nrc connected together,apparatus for releasing said switehes1 and a circuit including saidrelease eonductor and extending from one switch to another for operatingsaid apparntus.

i'. A telephone exch-inge system comprisinff telephone lines each.including n. pair of talltingr emwlnctm-s, automatic :oiniectors lesein nuinlie" than said telephone lines, sehn-tors less in number than thetelephone lines, subscribers individual switches corresponding in numberto the telephone lines, subscribers devices for closing together the twosides of the lines to control said indi vidual switches and selectorssind connectors, line circuits by 'which the said individual ,switchesand selectors and connectors are controlled to establish :i talkingcircuit between two of said telephone lines, cat-1i line circuitincluding said pair of talking conductors of a calling telephone line inseries, sind means inrlud'ingr release trunks separate from the talkingcircuit and extending respec-tively troni said individual switches tosaid selectors and from said selectors to said Connectors for restoring:zuid individual switches sind selectors nud connrctzrn-s by the.opening of the calling' lnrs.

8. A tolejilione exchange. System comprising :i scrondselect-or, a pairof talking conduotors extendingA thereto, and a battery 'haring our polegrounded said selector provided with a vertical line relny permanentlyconnected to non-grounded battery, with a rotary line relay permanentlyconnmcd to grounded battery, said relays normally bridged air-mss saidtalking conductors, :nid

with means for disconnecting said inlays from Said talking condurtors.

f). A telephone exchange system comprising. n pair of talking conductorsand a, rotary line relay normally connected to one of said conductors,an energizing circuit for Said relay, means for disconnecting said relayfrom and conductor, means for cousin short iinterruptions` in theenergizing circuit of said relay, and a slow-acting relay adapted toenergias when the seid line relay is energized, and adapted to romainenergized dur'ng the short interruptions in the energizing circuitof thesaid line relay.

l0. A telephone exchange system oomprising it selector provided with :i4side switch, e trunk line including a. pair of tolkugmonductors leadinto said selector, a circuit indudug said lking conductors in series forcontrolling the operation of said selector, a release relay forreleasing said;

selector while the side switch is in first or second position, und arelease relay for rclrasing the said selector when the side switch is inthird position.

l l. A telephone exdhangc system comprising a release relay 'providedwith three springs, and a catch on one sai/d springs adapted to lock heother twofn Silid springs together when t 1e release r,- ay e engine aside switch wipo` connecte( with (Jheef/Stile iprings, it trunk-releaseconductor, u sol/ector ting a private wiper, seid trunk-releaseconductor connecting another of said springs with said privato wiper,snid catch causing the locked pair of spi-in rs to be lirougtltt intoelectrical connection with the third springIr when the release relaydcincrgizcs to place the' side switch wiper in electrical connectionwith the said trunk-relense conductor.

IZ. A telephone exchange system wherein the Subscribete lines nachinclude a pair of talking conductors and wherein the central otliapparatus is controlled over circuits including the said talkingconductors in series, a selector und a trunk-releuse ronductor leadingthereto, a back-release relay for the selector, e second selector, arelease magnot therefor, said sewnd selector providt-.d with a sideswitch. and a release relay flor connecting the release magnet -with thesaid trunk-release conductor and back-release rclay whilel the sideswitch of the second selector in first or second position to cause thi`release oie the selectors while the side switch of the. set-ond selectoris in first or second position.

13. A telephone exchange sys-tcm comprising :i selector provided with uside switch, a release relay provided with a pair of springs, means forlocking:r said springs together, a release magnet, a rotary line relay,a :twitch shaft adapted to be raised step by .stt-p. a pair of springsadapted -to be operated by seid shaft, an armature for said releaseninguet, said armature adapted to unlock the rclease iclay springs whenthe release magnet energizes, and a private magnet adn )ted to bcenergized by the rotary line relay a ter the switch shaft is raised onestep to Close the shaft-controlled sp1-ings and only while the saidsideV switch is in fii'st'position.

14. A tele hone exchange system wherein a pair of ta king conductorslead to an air tornaticl switch, a switch Shaft, n rotar line relaynormally connected to one of sai talking conductors, means fordisconnecting said relay from said talking conductor, n private magnet,and un energizin circuit for said private magnet conti-ell by saidswitch shaft and rotary line relay, said shaft provided with means forraising :md rotating it, means operated by said shaft and relay forsetting up the said circuit while the rotar f line relay is energizedand the switch sha t out of normal vertical position but in normalrotary position, said cnergizin circuit when established. adapted to bebro (en either by the rotation of the shaft, by the denergizing of therotary line relay, or by both.

15. A telephone exchange system comprising a first selector, a second seector provided with a side switch, a trunk line including a pair oftalking conductors lcadingto'said second selector, a rotary line relaynormally connected to one of said talking conductors, means fordisconnecting said relay from said talking conductor, and means forenergizing said relay after the lirst selector extends conline wiper, a,rotary side switch wiper, a rotary line relay, a rotary line Wiper, arotary trunk conductor adapted to be switched by the rotary side switchwiper from the rotary line relay to the rotary line iwiper, a rotarymagnet, a side switch .wiper for closing circuit through the rotarymagnet While the side switch is in Vsecond position, a private magnet, aside switch wiper adapted to close circuit through the private magnet tolock the side switch in second position and to maintain circuit throughthe rotary magnet, a private wiper, bank contacts adapted to be engaged'by said private aviper, said ener gizing circuit maintained through therotary magnet adapted to he opened as soon as the private wiper passesout of engagement with busy bank contacts, a release magnet. a releaserelay' spring, and a side switch wiper for maintaining the releasemagnet in connection with the said release relay spring while the saidswitch is in first or second position, adapted for breal'ring suchconnection between the release magnet and the release relay spring whenthe side switch pases to third position.

17. A telephone system comprising a sec:

ond-selector provided with a private magnet. a switch shaft and springscontrolled there. by, a rotary line relay, a back-release rel-1y; a.private wiper, and a side switch provided 'with a switch wiper. 'saidprivate magnet having :i plurality of energizing circuits whereof one iscontrolled by the shaft-controlled springs and the rotary line relay,another of said 4circuits being controlled by the private magnet 'itselfand including said switch wiper and back-release relay and the privateaviper.

18.' A telephone system comjlirisiiig a bati tery haviiig'one polegrounder, a connector provided with a rotary line relay having oneterminal thereof permanently connected to ground, a vertical line relayhaving one terminal thereof permanently connected to the non-groundedterminal of the battery, a trunk line including a pair of talkingconductors and a separate conductor leading to said connector, aselector for establishing connection .with said three conductors, amagnet for releasn said connector, and. a circuit including sai separateconductor and extending from said selector to said connector foroperating said magnet.

19. A telephone system comprising a second selector, a connector, atrunk line includ ing a pair of talkin conductors and a separateconductor leading to said connector, a line relay for controlling theoperation of said connector to extend a connection therefrom, a circuitincludingsaid pair 'of talking conductors in series for energizing saidline relay, means for closing said circuit as soon as the selectorseizes said trunk line, a magnet for releasing said connector, and acircuit including said separate conductor extending from said selectorto said connector for operating said magnet.

20. A telephone system wherein the trunk. lines extending .between theautomatic switches each include a pair of talking con-Q ductors and aseparate conductor, a rotary line relay; a pair of line conductors,'asubstation high resistance coil, a vertical line relay, a circuit `forenergizing said rotary line relay, said circuitincluding said .line

conductors, said resistance coil, andsaid vertical line relay, theresistance of said circuit being adjusted to permit. the operation ofthe rotary line `relay and prevent the opera-r eacli including one ofsaid separate conduc.

tors and extending from one of said switches' to another for operatingsaid mechanisms. 21. An automatic telephone exchan es vstem comprising aconnector -provid with a rotary line relay, a trunk line includin apainof talking conductors and a sepa! te conductor leading to saidconnector, r selector for establishing connection with said threeconductors; a slow-acting release relay `adapted to energize when thesaid rotary line relay is energized, a magnetfor releasing saidconnector, and a circuit including` said separate conductor andextending from said se actor to said connector for operating saidmagnet.

loo

22. An automatic telephone exchange s vstem comprising a connectorprovided with a rotary line relay, a slow-acting` relay, an

energizing circuit for` the .slow acting relay,

4raid slow acting relay being provided with springs, and means forlocking said sprimgsA together when the slow acting relay is eneriso,

`gizing, said slow acting relayadapted to remain encr ized during shortinterruptions of the energizing of the said rotary luie relay.-

23. An automaticitelephone exchange sy? tem comprising a connector andmeans r seizingr 'said connector, the said connector being rovided witha slow acting relay adapte( to remain energized from t ie time theconnector is seized until the calling subscriber releases, a rotary linerelay, means for denergizin said rotary line re ay when the calling suscriber releases, means by which the denergizing of said rotary linerelay causes the deiicrgizing of said slow acting relay, a releasemagnet, a beveled stop, said slow acting relay provided with threesprings and with a latch for momentarily uniting said springs inelectrical contact, 4said latch adapted to strike said stop when saidslow acting relay is denergized, 'a release magnet and an ener izingcircuit therefor adapted to be opener by the separation'of two of saidsprings, substantially as set forth.

' 24. A telephone exchange system comprising 'a private magnet., avertical line relay, a rotary' line`r'elay, and a locking ener izingcircuit foro the private magnet-,adapte to be set up by the `verticalline relay and adapted tobe broken down by the rotary line relay.A

25.4 A telephone exchange s vstcmcompris ing 'a `vertical `line relay, arotaryV liuc relay, a side switch, and a locking energizing circuitadapted to be set up 'by the. lvertical line relayr while the sideswitch is in first or second position and adapted to be broke-ii by the,rotary line relay.

26. A telephone system comprising a private miignet, a side switch andprivate wiper, a rotary line relay and a release magnet, a circuit forinitially energizing said private magnet, a lookin circuit for saidprivate magnet controlle by said rotary line relay, a. couple ofenergizing circuits for said re lease magnet, one of which circuits iscontrolled by theprivate magnet adapted to be set u while the sideswitch is in second, position and the private wiper on a groundedcontact point at the instant that t ie rota-ry line'zrelay breaks thelocking circuit of the private magnet.

27;; A telephone system -comprising a verticalline relay, a si e switch,a rotary magnet controlled by the vertical line relay while the side'switch is insecond position, a sha-ft andsliaft wipers rotated therebyin Aa, step by stepmannerfa 'private wiper, a release magnet, anenergizin circuit therefor, established while the si e switch is insecond sitioxi, comprising private magnet sprin gid adapted to beestablished whenever t e private wiper stops upon a vgrounded contactoint, and a ocking ener 'zin circuit for t e private magnet adapte toestab- 1.11am 1e lished by the vertical line relay upon its firstoperation, after the side switchpassesto'second position, in order tomaintain the said private springs separated, and to prevent theestablishment of the said release magnet energizing circuit while thepri- Yate wiper is sing rotated.

28. A telephoneisystem comprising a. connector side switchfwerticul androtary line relays for operatingsaid side switch, and a private magnet,said side switch controlled )y the privatemagnet und adapted to shiftfrom first to secondposition and from second to third position, theshift from first to second position produced by'the vertical line relayenergizing the yprivate magnet and locking the latter, and by the rotaryline relay subsequently breaking down the said locking circuit,`theshift from second to third position produced by the vertical line relayagain energizing and locking the pri: "ate magnet, and by the' rotaryline rela'l subsequently breaking down the lockingfci cuit.

29. A telephone system comprising a vertical liiie relay, a verticalmagnet, and aA ri- .vate magnet combined to energize toget er.

30. A telephone system comprising a selec tor, a side switch therefor,another selector for extending connection to 'said first mentionedselector, a rotary line relay for said first mentioned selector adaptedto energize as soon as the first mentioned 'selector is seized, a slowacting release relay energized thereby, said siow acting release` relayremaining in readiness to release said selectors if the subscribershould desire to do so before said side switch passes to third position.

31. A telephone system comprising trunkscleotors provided with linerelays, means for cutting oil' said relays, connectors provided withpermanently bridged line relays, a battery permanently connected inseries between tlie relays of t e connectors, trunk-release circuits forthe selectors controlled by the connectors, telephonelines, and linecircuits for successively controlling one or more of saidtrunk-selectors and a connector to ex tend connection to a calledtelephone line, each circuit including the two sides of a calling,rtelephone line in series, and means for re easing the selectors andconnectors by the openin of a connected telephone lino.5

32. telephone system comprising trunkselectors, line relays for saidselectors, operating circuits controlled by said relays, means forcutting o said line rela-ys, automatic lconnectors, line relays `forseid connectors,

circuits controlled by said last inentioued''clays for controlling the oeration thereof t0 extend connection there om, a, source of operatingcurrent, said source of current normally bridged between the relays ofthe connectors,metal1ie line circuits for controlling with a linetherein, selectors less in'numher` than the telephonelines,'subscri'bers individualswitches correspondingin number to thetelephone lines, subscribers devices for closing together the two sidesof` the, lines to-control said individual switches and selectors andconnectors, said individual switches and selectors and connectors arecontrolled to establish a talking circuit between two of said telephonelines, each line circuit including-said pair-of talking conductors of acalling telephone line ing4 a second-selector,

in series, and means including releasetrunks separate from the talkingcircuit aiidcxtending respectively from said individual switches to saidselectors and from said se-V lectors to said connectors for restoringsaid individual switches and selectors and connectors by the opening oftheV calling line.

34.. A telephone exchange system comprisa pair of talking conductorsextending thereto, and a battery having one pole grounded, said selectorprovided with means having vertical motion from' one operative level toanother to select groups or divisions of the exchange, and rot v motionin any selected level to connect a'ith a line therein,' and providedalso with a vertical line, relay permanently connected tov nongroundedbattery, with a rotary line relay permanently connected to grounded bttery, said relays normally ing conductors, and meansfor disconnectingsaid relays from 4said .talking conductors.

25. A telephone exchange system compris ing4 a selector provided withmeanshaving veit'ical` mor on from one level to another to select gmupsor divisions of the exchange, and rotary motion in any selected level toconneet. with aline therein, and prpvided also with a side switch,'avtrunk line including a pair of talkingI lector. a circuit includingthe saidtalking conductors in series for controlling the operation ofsaid selector, a releasejrclay for releasing said selector while thesiileuswitch is in first or second position, and a release relay forirleasin, i,v the said selector'zwhen thesid'e switch is in thirdposition. j i

A telephone ei'cchange system comprising a'selector provided with meanshavingr vertical motion from one'operative level to another to selectgroups or divisions of the exchange and rotary motion in any selectedsprings line circuits by which the bridged across sai l talk-`condiictors leading to said .tvnding'froin said to another tust-.lectgroups or egrchange and rotary motion 1 n any selected: a trunk?.

a line therein andfprovided also with a side switch, a release relayrovided with a pair of springs, means for ocking said` springs together,a release inagnet, a rotary line relay, a switch shaft adapted to beraised step by step, a pair of springs adapted to be operated. by saidshaft, an armature ture adapted to unlock the release' relay when therelease magnet energizes, a private magnet `adapted to be energized b `Pthe rotary line relay after the switch sha-t is raised one step to closethe shaft controlled springs, and only while the said side switch is infirst position.

37. A telephone exchange s istem comprisin a first selector,'a seconselector provi ed with means having vertical motion level to connectwith rom one o rative level to anotherto select line includinga :pair ofleading to said second' -line relay normally con-` nected to one ofIsaid talking ccnductors for said release magnet, said jarmameansfor'disconnecting said relay from' sai( 1 talking conductor, and meansfor energizingsaid relay after the first selector extendsv ronnection tothe second selector adapted to 95 maintain the relay energized as longas the side switch of the second selector remains in first or secondVposition.

38. Aitelephone system permanently connected to ground, a4 vei'-,`having one terminal thereofA tical line relay permanently connected tothe non-grounded terminal of the battery, a trunk line including a pairof talking conductors and a separate conductor leading to said conncctoi',

includingi,r said separateconductor and cxfoig operating said inainiet.4A

, 39.' n telephone system roiiiprising a'seol ond` selector,arconnei-tor provided with.'

means having vertical "motion from o`ne level` level to connect with a'li'iie,'t|ieri 'i`iif., line'inriudiiiga pair of talkingcondiietorsand` a'separate conductor leading to said connector, a line relay forcontrolling the operation of said connector to extend a connectiontherefrom, a oli-enit including said comprisingl a bnttery having onepole grounded, a connector i a selector for establishing, 'connec-' tionwith said thine conductors, a magnet,A Y for releasimgr said connect/or,and a circuit r selector to said connector iid di visions of the. i

pair of talking,conduetorsin series for energizing said line relay,means for closing said circuit as soon as the selector seizes said trunkline, il magnet for releasing said connector, and ai circuitincludinglsaid separate conductor and extending from said Selector tosaid connector for operating said magnet.

40. An automatic telephone exchange system comprising a connectorrovided with means having vertical motion rein one operative level toanother to select groups or divisions ofv the exchange, and rotarymotion in any selected level to connect with :i line therein, andprovided also with a rotary line relay, a trunk line including a pair oftalking conductois and a separate conductor leading to said connector, aselector for establishing connection with said three conductors, aslow-acting release relay adapted to energize when the said rotary linerelay is energized, a magnet for releasing Said connector, and a circuitincluding said separate conductor and extending from said selector tosaid connector for operating Said magnet.

41. `An automatic telephone exchange system comprising a connectorprovided,with means having vertical motion from one operative level toanother to select groups or divisions of the exchange, and rotaryniotion Ain any selected level to connect with a line therein, andprovided also with a rotary line relay, a slow-acting relay, an energizals . provided with means havin ing circuit for the slow-acting relay,said slow-acting relay being provided with a pair of sprin and means forlocking said springs toget er when the slow-acting rela' is energizing,said slow-acting relay adiipted te remain energized durin interru tionsofthe energizing of tie said rotary ine relay.

42. An automatic telephone exliange system comprising a connector, meansfor seizing said connector, the said connector being tion from oneoperati veleve to another to select groups or divisions of'the exchange,androtnry motion in any selecter level to connect with a line therein,and also roadapte to remain energizedv :from the time the connectorlsvseized until the calling subscriber releases"a rotary line relay,means for deenergizing saidrotary line relay when the calli 4suloscrlxirreleases, means by which the' enegizing of said rotary line relay iycauses the denergizing of said 'slow-acting seid slow-acting relayigdeiiergiz rela e release ma et und a beveled stop, sai slow-acting. aprovided with three springsand with o etch for momentarily uniting saidspringsin clectricelcontact, saidflotch adapted to vstrikesaidstoei'yrhen short i -endwse-movab e switch shaft,

aving vertical motionv a source of operating current, said conne'o utors each manently ridged line relays permanently Connected with saidsource of current, and circuits each including e pair of said talk-'-grovided with one or more pering conductors in series for energizingsaid?.

line relays to control the said connectors in their group selecting andline connection operations. v

44. In a telephone exchange trunking systcm` a telephone line, anautomatic switch rovided with a bank of contacts Aarranged in aplurality of levels, and with a rotary switch shaft adapted to be raisedto any one osaid levels .in "accordance with n digit of the callednumber, a subscribers device for closing together the two sides ofgtheline,

adapted to comentorest before actuation thereof to transmit impulsesfor,tlienext d igit, means includin l ,sive to the closing o tli e linefor`` raising the switch shaft, adatedltoatep t'hcj latter, a 4ing';tothe numberfofa* times the hneisclosedtmeans onautomati- V up toany level,a

cally rotating the,. sl1lii at any level to find an idle contacttherein, means -for cutting f oli the line 'reloyf while the shaftis inits rotated eration,V und means for restoring the Switchs 4aft. tonormalfposition by theopen: ing of the line. i

45. In s. tele hone exchange sys"A .1 iierls telephone' line, .iin.;entgik..v matic switch irovidedwith, a rotary-Find tem, a Subseri a. linerelay respoiiendwise-movab e switch snafu a' linejfreldy.

. for controlling the `endwiscI movementsof said shaft, means includinganotligrliii i,

lay for controlling thenotiition ojtlxehd i line circuits for eneringsaid releff for cutting of seidglrzelayefwhle is in its rotatedposition, including the two sides of the teleplio' if! series andailing` L vtrolling lsaid eircuit,;`ndd t "to rest u tieolsaid slhaft- Mno. tee ione exc 'ange trun tern, alsubscriliers telephone line, an,iiiiioi15 matie' switch rovided with it Y mltlr'fd" matic switch, atrunkfline'includui` n vthe eompletiono the heiidyvisel"1' of talkingconductors Eand a 'se crate conductor leading from 4said. 4first s.w1tchtosaid other switch, means including -a line circuit for controllin theendwise movements of the switch sha t, means including a line circuitfor controlling the rotation of the shaft to seize said trunk line, eachline circuit includmg the two sides of the telephone line and said pairof talking conductors all-in series, means for controlling said circuitsadapted to return to normal ,upon the completlon of the endwise.movement 4of said shaft, release mechanism for said first switch, and'a circuit includin saidseparate conductor andcontrolled Ey said otherswitch oroperatingsaid mechanism; t

47. In a telephone exchange trunlring system, telephone lines eachincluding 'a pair of talking conductors, automatic connectors less innumber than said-telephone lines, se-

lcctors less in Anumber than the telephone lines, subscribers individualswitches" corresponding 1n .number to-thetelephone lines,

subscribers devices for closin ntogether the -two sides of the lines tocontro said individ.

ual switches and selectors'and connectors, each device adapted to cometo rest afterone digit and beforecalling the next digit, line circuitsbywhich the'said indiyidual switches `and selectors and connectors arecontrolled tn establish a talking circuit between two Y of saidtelephone lines, each line circuit inycluding thetwo sides of fa callingtelephone line in series, and meansiincludinglrelease trunks separatefrom the talking circuit and i l extending respectively fromsaidindividual switches to said selectors and from said se lectors to saidconnectors for restorin said individual switches and selectors'an conynectors by the openingr of the calling line.

A48. In a telephone trunking system, 'trunkselectorsfline relays iforcontrolling said se lectors, means for cutting oil' said line relays,

' automatic connectors, line relays for said connectors, a source ofoperating current, said source ofcurrent normally bridged. between therelaysfof the connectors, trunk. release circuits for the selectorscontrolled by the connectors, and means for controlling to,come to rest4after each separate o rationthereof `for each digitof the call.-number. E

'49.1 In 'an .automatic telephone exchange system employing.liridginghne relays, a calling telephone hne,a called telephonel line,a. series of automatic switchesv for extendin connection from thecallin' line to the cal edline, having precisions or automaticallyreducing the number of bridges across the talking circuit during theestablishment thereof, three-conductor trunks between said switches, anda plurality of line circuits by which said switches are successivelycontrolled,each said line circuit in-H for closinig'together the twosides offth'e Sill and connectors are controlled, 'elichlincircludingthe two sides of the calling line in series.

50z In a telephone exchange system ein; ploym`g-bridgmg line rela s, acalling 4telehone'hne, a called telep one line, means including aplurality of,selectors` and a .connector for extending connection fromthe calling line to the called line, having provisions for automaticallyreducing the number of bridges across the talkin circuit during theestablishment thereof, tiree-conduc 75 tor trunks between said switches,line circuits for controllin the selectors, and line circuits forcontrol ing the connector, each line circuit including the two sides ofthe callin line in'series.

51. n a telephone exchangesystem employing bridging line relays, asubscribers telephone line, an automatic switch provided witha rotaryand endwise-moyable switch shaft, haring provisions for automaticallyreducing. the `number of bridges across 'the talking' circuit duringVthe establishment thereof, m'eans including a line circuit forcontrolling the endwise movements of the l switch shaft, lneansincludinga line circuit 90 for controlling the rotation of the shaft, and atrunk-releasecircuit for restoring said switch, each line circuitincluding the two sides of the tele hone line in series, 1

52.. In a te ephone system employing bridging line relays, a line, aplurality of electrically-propelled and stcp-bystep` actuated switcheshaving provisions for au' tomaiically reducing the number of bridgesacross the talking circuit during the estalr lishment thereof,three-wire connections between said switches, line circuits forsuccessively controllingsai switches-and a subscriber-s device forintermittently closing to# gether the two sides of the line to establishsaid circuits, each line circuitin'cluding the two sides of the line inseries.

53. In a telephone exchange stem employing bridging line relays, telepone lines, automatic connectorsA lless in jnumber/ than 'said` telephonelines, selectors less in number than thetelephone lines, havingprovisions for automatically. reducing the number ofv bridges across thetalking circuit during l the establishment thereof, subscribers in idividual Aswitches corresponda in number to the telephone lines, subscri4 '"rlmes to contro V individual swtches lectora and connectors, lmecircuits M the saidindividual switches:luideselectors'`-` cuitincludingthe two sides'offycalli? telephone line in and means inclu ingrelease trunks for restorin said. ind` vidual switches and selectors anconnectors by the opening .of the callin lines.

54. In a telephone systgem employing by sich.. 1?"

ist

lef

bridging line relays, subscribers telephone lines, automatic means fortrunkin a, calling line into connection with a cal ed lino, havingprovisions for automatically reducinf,lr the number of bridges acrossthe talking circuit during the establishment. thereof. includingthree-wire trunks, and successive line circuits for controlling saidautomatic trunking means, each line circuit including the two sides ofthe calling telephone line in series.

55. In -a telephone system employing bridging line relays, trunkselectors having provisions for automatically reducingr the number ofbridges across the talking;` circuit during the establishment thereof,line relays for controlling:r said selectors, means for cutting 0H saidline relays, automatic connectors, line relays for said connectors forcontrolling the operation thereof to extend connection therefrom, asource of operating current, said source of current normally bridgedbetween the relays of the connectors, and trunk-release circuits fortlie selectors controlled by the connectors.

56. ,An automatic telephone exchange system comprising subscriberslines, a series of automatic switches for trunking a calling subscribersline into connection with culled subscribers line,.a brid e containingan operating element and a ridge cut-o` relay for each subscribers line,trunk lilies each 'Y including a pair of talking conductors and aseparate conductor between said switches. circuits each including a pairof said talking.,r conductors in series for operatingr said switchesineens independent of the earth :it the calling subscribers station forcontrolling said circuits, a magnet for releasing the final one of saidseries of switches, and a circuit including said separate conductor ofone of said trunk lines for operating said magnet.

57. An automatic telephone exchange sysI tem comprising a callingtelephone line including a air of talking conductors, a called telephoneine, a series of automatic switches for extending' connection from thecalling line to the'ealled line.- a bridge containing an operatingelement and a bridge out oil' relay for each telephone line, trunklines, each including a pair of talkingconductors and a separateconductor vgytvlveen said switches, a plurality of line cii lits bywhich said switches are snccessircly controlled, each said line circuitincluding said pair of talking conductors of the calling line inlseries, a magnet for releasing thefinal onel of said series of switches,and a circuit including said separate conductor of onoof said trunklines for operating said'magnet.

58; .A telephone exchange system comprising a calling telephone lineincluding a pair of talking conductors, a called telephone line, meansincluding a plurality of selectors and u connector for extendingconnection from a calling line to a called line, a. bridge containing'an' operating element and a brid e cut oli' relay for each telephoneline, trim lines each including a pair of talking conductors and a.separate conductor between said switches, a. plurality of line circuitsfor controlling each of said selectors, a plurality of line circuits forcontrolling` said conncctor, cach of said line circuits including saidpair of talking conductors of the calling line in series, a magnet forreleasing said connector, and a circuit including,7 saidV separateconductor ofone of said trunk lines for operating said magnet.

59. A telephone exchange system comprising a calling telephone lineincluding a pair of talking' conductors, u called telephone line, a,connection between said lines, auto matic switches for establishing saidconnection, a bridge continuing an operating element and a bridgecut-ofi relay for nach telephone line, a trunk line including a pair oftalking Conductors and :i separate conductor between Said Switches,means for sie;Q nailing the called subscriber by closing to gethcr saidpair of talking conductors of the calling' line after the two ,lines areconnected together, a magnov for releasing one of said switches, and acircuit including,r said separate conductor for operating said mug` net.

G0. A telephone exchange system comprising telephone lines eachincludingT a pair of talking conductors, a. bridge containing anoperatingelenient and a bridge cut off relay for each tele lione line,automatic connectors less in num er than said telephone lines, selectorsless in number than the telephone lines, subscribers individual switchescorresponding in number to the telephone lines,

trunk lines each includingr a pair of talk- 'ing conductors and aseparate conductor,

some of said trunk lines extending between said selectors and connectorsand other of' said trunk lines extending between said individualswitches and selectors, subscribers .a calling telephone line in series,and means including release circuits for restoring'said individuelswitches and selectors und connectors by the opening of said pair oftalking conductors of the calling line, each said release circuitincluding said .separate cony ductor of one of said trunk lines.

61. In a telephone system a called tolephone line, an automatic switch,a. trunk line including a peirof talking conductors leadduring the useof the latter for talking pur- 1o in thereto, means for ma ingconnection to poses.

seid trunk line, means for controlling said Signed by mc at Chicago,Cook county, pair of talking conductors in series to conllinois, this12th day of April, 1907.

trol Said switch to connect with said called line, said switch having econtrolling mag- RAYMOND H' BURFEND not connected to one of said talkingcon- Witnesses:

ductors, and means whereby seid magnet, is EDWARD D. FALEB,

disconnected from said talking conductcr ARTHUR B, SPERRY.

